Underreamer



Dec. 19, 1922. 1,439,093. C. B. GIBSON, JR.

UNDERREAMER.

FILED OCT. 10, 1921- 2 SHEETS-SHEET I- [Ia/mama:

d m/ G-Z5awn,Jn, ,q w W977 A Dec. 19, 1922.

l! 3 [III i C. B. GIBSON, JR.

UNDERREAMER.

FILED OCT. 10, 1921.

2 SHEETS-SHEET 2.

i I I A 1 1' e 4d \W 4d 6 /M, lnzzeniwm Patented Dec. 19, 1922.

UNHTEKE STATE CABLETON' B. GIBSON, JR.,

OF SAVANNAH, GEORGIA.

UNDERREAMHER.

Application filed. October 10, 1921. Serial No. 506,818.

To all'whom it may concern: I

Be it known that I, CAnLn'roN B. G-nsson, Jr., a citizen of the United States, and mmdent of Savannah, Georgia, have invented certain new and useful Improvements in Underreamers, of which the following is a specification.

An object of my invention is to provlde a practical tool which may be passed thru the casing of a well or similar hole and expanded for drilling on enlarging said hole beyond the lower extremity of said casing to a predetermined diameter larger than that of the casing.

A further object of my invention is to provide a practical under-reamer which may be collapsed or contracted and easily with; drawn from the hole thru the casing.

A further object of my invention is to provide such an expansive tool without the use of springs in any form, the action of such tool being entirely independent of any spring or similar device.

A further object of my invention is to provide such a tool of a design which will reduce to a minimum the strains set up in the pivot pin during operation of the tool.

A further object of my invention is to produce a practical under-reamer which after expansion into the working position becomes positively locked in such position until voluntarily unlocked and withdrawn by applying tension to the drill stem to whichthe tool is attached.

A still further object of my invention is to provide a practical tool which, while capable of performing all the functions of similar tools now in use, is of the utmost strength and of such simplicity in form and number of parts that it can be manufactured at a minimum cost of production.

Other objects of the invention will appear in the following detailed description and drawings, in which drawings:

Figure 1 is a longitudinal vertical section thru the improved under-reamer, showing the tool expanded and locked in the working position.

Figure 2 is a longitudinal vertical section at right angles to Figure 1.

Figure 3 is a longitudinal vertlcal sectlon similar to Figure 1, but showing the barrel slightly raised, the cutters'unlocked and in the position for closing.

Figure 4: is a similar longitudinal vertical section the plunger raised and the cutters in the closed position.

Figure 1 shows a transverse the plane A-A in Figure 1.

Figure 1 shows a similar section but along the plane B-B in Figure 1.

Figure 2 two interchangeable cutters.

Referring to the drawings in detail, wherein similar reference characters designate corresponding parts thruout the several views, the numeral 1 designates the hollow cylindrical barrel which is closed at its upper end by the cap 2 which, if desired, may be made integral with the barrel 1, but is preferably threadably connected to the barrel 1 at 2 and furnished with a tapered threaded portion 2' for attaching to any standard tool joint, not shown. rel l is provided at its lower extremity with two diametrically opposed round holes 1 thru which is inserted the pin 6 which is held in place by. the head 6" and the cotter pin 6". The barrel 1 is further provided at its lower extremity with two opposed slots 1 situated approximately on a diameter at right angles to the diameter passing thru the holes 1", the said slots being for the purpose of receiving the portions 4 of the cutters 4, preventing the too great expansion of the cutters and holding the cutters in place during the rotation of the tool when section along -1n operation. The barrel 1 encloses the plunger '3wvhich fits loosely or slidably in the barrel and is co-axial with it and of such length that, when the cutters 4 are expanded to the cutting or operating position and raised into locking engagement with the slots 1 as shown in Figure l, the lower end of the plunger 3 rests on the upper portions of the cutters 4 and the fillers 5 at 8 while its upper extremity is held against upward movement by the under surface of the cap 2 at 2, which thus constitutes a stop. The inter-changeable cutters 4, one of which is shown in Figure 2 preferably made from one piece of steel by the drop forging process, are formed with upper cam portions 4 which support the weight of the plunger 3 at 3, which weight tends to force the lower or cutting portions 4 apart and to hold them in the open or cutting position. Each cutter is also provided with a slot 4 thru shows a plan view of one of the The barwidth slightly greater than the diameterof the pin and of a length greater than the pin diameter by the length of the pre-determined amount of the movement of the plunger 3 along the axis of the barrel 1. The cutters 4are further provided with an upper portion so formed as to furnish the proper clearance within the barrel 1 when the cutters are contracted for insertion or withdrawal from the casing, not shown. The fillers 5, held in place by the pin 6, are preferably made of cast iron or steel of such shape that they completely fill the spaces between the faces of the cutters and the inside of the barrel, as shown in Figures 2 and 1", thereby preventing the entrance of earth or stone into the barrel 1 from below.

The operation of the tool is as follows:

The tool being attached to the drill stem and thereby suspended over the mouth of the hole, the cutters are forced together against the weight of the plunger and held in the closed position as in Figure 4 by means of any convenient form of clamp, not shown in the drawings. The lower or cutting end of the tool is then inserted into the upper end of the casing and the clamp removed. During its descent the cutters are prevented from openin 'b the inside wall of the casing against which t ey are pressed by the action of the heavy plunger 3 but, immediately after clearing the lower end of the casing, the cutter blades being no longer confined, the weight of the plunger acting on the cam portions of the cutters causes the lower portions of the cutters to separate as shown in Figure 3. Further downward movem'entl of the cutters is arrested by their coming in contact with the material to be removed but the weight of the drill stem and barrel cause the barrel to continue its descent until the barrel and its pin take the position shown in Figure 1. In this position the center of the pin is no longer in the center of rotation of the cutters and contraction of the cutters is thereby prevented. Furthermore, when the tool is in this position the whole Weight of the drill stem is applied to the plunger thru the barrel cap which absolutely holds the plunger down on the upper portions of the cutters positively preventing their closing or even bringing any undue strain on the pin. In the operating position the cutters are prevented from further opening by the shoulders 4 resting against the upper ends of the slots 1* and the whole tool is therefore positively locked and rigid in position.

To remove the tool, it is only necessary to raise the drill stem, thereby raising the barrel, when the weight of the drill stem is removed from the plunger, allowingthe lunger to move in relation to the barrel, the pin returns to the center of rotation of the cutters, unlocking them, when the pressure of the casing at 4 closes the cutters against the Weight of the plunger and allows the complete tool to be withdrawn thru the casing.

Having thus described my invention what I claim is:

1. An under-reamer comprising a barrel having blade receiving slots and a transverse pin, a pair of reversely placed cooperating blades having reduced portions to fit within said barrel, said reduced portions'having elongated slots engaged by said pin, and a plunger movably located in the barrel and cooperating with the upper ends of the blades.

2.. An under-reamer comprising a barrel having blade receiving slots, a pair of reversely placed cooperating blades having reduced portions to fit within the barrel, said reduced portions having substantially vertically elongated slots, a pin carried by the barrel engaging said slots, a plunger slidable within the barrel and cooperating with the upper ends of the blades to swing them into engagement with said slots, and stop' means on the barrel for limiting the upward movement of the plunger whereby the weight of the drill barrel and drill stem is transmitted to the blades when in expanded position.

3. An under-reamer comprisin a barrel, a pair of reversely placed blades havin reduced portions held in said barrel to ave limited sliding movement therein, said reduced portions being so shaped as to hold the blades against pivoted movement when retracted in the barrel and permit such pivotal movement when extended, and a gravity plunger cooperating with the upper ends of said reduced portions and tending to spread the blades.

4. An under-reamer'comprising a barrel, a transverse pin at the lower end thereof, a pair of reversely placed blades having ofiset reduced portions provided with lengthwise elongated slots, said reduced portions having parallel walls fitting the inner walls of the barrel and having curved portions concentric with the upper ends of the slots, and a plunger cooperating with the upper ends of said reduced portions.

5. An under-reamer comprising a barrel,

a transverse pin at the lower end thereof,

a pair of reversely placed blades having offset reduced portions provided with lengthwise elongated slots, said reduced portions having parallel walls fitting the inner walls of the barrel and having curved portions concentric with the upper ends of the slots, and a plunger cooperating with the upper ends of said reduced portions, said barrel having stop means for limiting the upward movement of the plunger.

6. An under-reamer comprising a barrel, a transverse pin at the lower end thereof, a pair of reversely placed blades having offset reduced portions provided with lengthwise elongated slots, said reduced portions having parallel walls fitting the inner walls of the barrel and having curved portions concentric with the upper ends of the slots, and a plunger cooperating with the upper ends of said reduced portions, said barrel having a closed upper end coacting with the upper end of the plunger.

7. An under-reamer comprising a barrel, a transverse pin at the lower end thereof,

a pair of reversel y placed blades having oilset. reduced portions provided with lengthwise elongated slots, said reduced portlons having parallel Walls fitting the inner walls of the barrel and having curved portions concentric with the upper ends of the slots, and a plunger cooperating with the upper ends of said reduced portions, said barrel having a stop cooperating with the plunger to limit the movement of the plunger to an amount approximately equal to the length of the slots in the blades.

8; An under-reamer comprising a barrel having diametrically arranged slots in its lower 'edge and a bearing member transverse to the plane of said slots, a pair of reversely placed blades having ofl'set'portions slidably fitted within the barrel, said por-' tions having elongated slots engaged by said bearing member and having upper edges disposed at right angles tosaid slots, each of said portions having parallel side edge portions terminating in curves substantially concentric with the upper end of the slot therein, a plunger freely mounted and arranged tobear on the upperv edges of the 0E- set portions of the blades in the barrel, and means for limiting the upward movement of the plunger.

CARLETON B. GIBSON, JR. 

